Ingo Molnar wrote:> * Al Boldi <a1426z@gawab.com> wrote:> > > ok. I think i might finally have found the bug causing this. Could> > > you try the fix below, does your webserver thread-startup test work> > > any better?> >> > It seems to help somewhat, but the problem is still visible. Even> > v20.3 on 2.6.22.5 didn't help.> >> > It does look related to ia-boosting, so I turned off __update_curr> > like Roman mentioned, which had an enormous smoothing effect, but then> > nice levels completely break down and lockup the system.>> you can turn sleeper-fairness off via:>> echo 28 > /proc/sys/kernel/sched_features>> another thing to try would be:>> echo 12 > /proc/sys/kernel/sched_features>> (that's the new-task penalty turned off.)>> Another thing to try would be to edit this:>> if (sysctl_sched_features & SCHED_FEAT_START_DEBIT)> p->se.wait_runtime = -(sched_granularity(cfs_rq) / 2);>> to:>> if (sysctl_sched_features & SCHED_FEAT_START_DEBIT)> p->se.wait_runtime = -(sched_granularity(cfs_rq);>> and could you also check 20.4 on 2.6.22.5 perhaps, or very latest -git?> (Peter has experienced smaller spikes with that.)

Ok, I tried all your suggestions, but nothing works as smooth as removing __update_curr.

Does the problem show on your machine with the 3x gears under X-vesa test?